For example, JP-2005-291030A describes a vehicle control system in which an engine is compulsorily brought into idling state when an accelerator pedal and a brake pedal are simultaneously stepped over a specified amount.
However, it is not specifically described how to bring the engine into idling state when an accelerator pedal and a brake pedal are simultaneously stepped. Generally, regarding a gasoline engine equipped with an electronic throttle system, following techniques can be conceivable as an output-reducing control by which the engine is brought into idling state.
(1) An accelerator signal input is set to zero so that a throttle-valve command value, which is transmitted to a throttle actuator, is decreased to a value corresponding to idling state.
(2) A throttle-valve command value transmitted to a throttle actuator is compulsorily decreased to a value corresponding to idling state.
(3) A throttle actuator is deenergized so that a throttle valve is compulsorily closed by a biasing force of a throttle return spring.
(4) A fuel injection is not intermittently performed to reduce an engine output.
(5) An ignition is not intermittently performed to reduce an engine output.
However, in the above output-reducing controls (4) and (5), it is likely that exhaust gas becomes rich or lean so that emission is increased and a catalyst is deteriorated.
Also, in the above output-reducing controls (2) and (3), other controls, such as traction control, electronic stability control, and cruise control are canceled by the output-reducing control. Thus, the throttle valve is compulsorily closed, whereby drivability may be deteriorated.
In the above output-reducing control (1), since the accelerator signal input is compulsorily changed, it is likely that the engine output can not be sufficiently decreased due to other inputs.